When Would I Notice Size Differences in Carat Weights?

What carat size should I choose? Would I be able to notice a difference between 2 diamonds that are 0.3 mm apart? When would I start noticing visual size differences with diamonds from various carat weight brackets?

If you are one of the people with these questions in mind, don’t worry, you aren’t alone. In fact, I get asked questions like these frequently via emails and decided to create this blog post to answer them.

First things first, let’s address why people ask these questions.

Since we are talking about an engagement ring that probably costs thousands of dollars, I can tell you that the fundamental reason is always related to cost. After all, who doesn’t want to make a purchasing decision that gets you the best value for money.

Diamond Prices Have an Exponential Relationship With Carat Weight

Diamond prices jump at every 10 points (0.1 carat). For example, a 0.50 carat diamond would cost about 30% more than a 0.40 carat diamond with similar specifications.

Yet, the real difference in size between these 2 stones is roughly 0.4mm. And if you pick up a ruler and look at the subdivisions, a 0.4mm difference might not be that big of a size difference.

Ruler showing 1mm markings

To help with visualization of different sizes, I’ve compiled a printable chart of real-life diamond sizes and their relative carat weights. Click here to check it out and download a copy in .pdf format.

The Key Question Is: Can You Tell The Differences?

Weird as it seems, people tend to notice the 0.4mm difference when comparing objects of smaller sizes. When comparing bigger objects, our brains seem to perceive the same difference as insignificant.

Let me show you some examples to illustrate this…

4.8mm vs 5.2mm

Do you see the difference of 0.4mm between the 2 circles above? Well, most people do notice this subtle difference when they compare a 0.40 carat diamond against a 0.50 carat diamond.

7.4mm vs 7.8mm

In contrast, the same physical difference of 0.4mm between a 1.50 carat diamond and 1.75 carat diamond isn’t readily detected because of the way our brain works.

If you want to get a high quality engagement ring and better value for your money, I highly recommend vendors like James Allen, Whiteflash and Brian Gavin where you can visually see exactly how the diamond looks like.

Here Are a Few Other Examples to Check Out…

6.2mm vs 6.5mm

Also, what happens if I place the diamonds further away from each other?

Do you realize it is harder to notice size difference now? In real life, most people casually observe diamonds from a distance and it isn’t easy for them to pick up minute differences.

Now, for people who intend to buy diamonds within the 0.50 – 0.75 carat ranges, I performed another comparison to help you visualize how they would look like in reality. If you refer to the image below, I think it is pretty clear that you would notice an obvious size difference.

5.2 mm – 5.8mm

Ultimately, Your Opinion Is What Matters Most!

So, what do you think?

Perception is more of a subjective matter than an objective one. Some people see differences in sizes easily and some don’t. It is the same with diamond color where some individuals can see clear differences between F and G color diamonds whereas the majority of us don’t.

I know of people who are psychologically affected by the size of the diamond in their minds. Even if they are wearing a 0.92 carat diamond, in their mind, it is never good enough unless it is a 1 carat diamond.

At the end of the day, go for a carat size that’s “mind-clean” and affordable to your wallet. After all, diamonds are purchases which are meant to be enjoyed instead of being something that constantly frets you at the back of your mind.

If you are looking for a diamond that is cut to the best standards and optimal light performance, I recommend checking out Whiteflash and Brian Gavin. Their signature diamonds look spectacular in real life and represent the top 1% of well-cut diamonds in the market.

On paper, it seems like an OK choice. However, I won’t recommend buying a pear shaped based purely on paper. There are some aspects like bowties and light performance factors that a grading report won’t tell you.

In reality, you won’t be able to see differences with the naked eyes between a VS diamond and an IF diamond. That’s why I think it is a waste of money unless you are looking for symbolic reasons for an internally flawless stone.

cherri gibson-

March 30, 2017 at 2:08 pm

Hi there, i am looking at a tiffany. Vs1 and h in colour. All papers say excellent cut. It is platinum. But the stone is a tiny .21 on my large fingers. The seller wants £500! What do you think?

Paul Gian-

March 31, 2017 at 12:23 am

This deal sounds dodgy to me because a real and original platinum setting from Tiffany & Co would cost more than £500. If the vendor has the original certificate and can prove that it is an authentic Tiffany ring, I think it is a decent buy. As for the diamond being small for your fingers, I’m not sure what kind of carat sizes you are expecting here. Are you expecting to get anything larger than 0.2 carats realistically with that budget range?

Romayne-

April 7, 2017 at 4:08 pm

Hi Paul, Took your advice and checked out James Allen, love it! On the GIA reports, what refers to the cut? Is it the polish/symmetry characteristic? Is it better to have a higher grade on the polish or the symmetry or do both go together and should be excellent all around?

Paul Gian-

April 8, 2017 at 1:57 am

Depends on the shape of diamond you are looking for. If you are looking for round brilliants, polish and symmetry would be important factors to keep at excellent ratings. For fancy shape diamonds, they aren’t necessarily that crucial and you will need other information such as videos/ASETs to help you determine cut quality.

Jerring-

September 12, 2017 at 8:35 am

Hi Paul,

Is it worth to buy a 0.31 GIA certified internally flawless Ex Ex Ex cut grade in f colour or should I buy a bigger size with a bit less of the quality?

Thanks!

Paul Gian-

September 12, 2017 at 8:56 am

Ask yourself, why do you need the IF clarity for? If you need it for symbolic reasons, by all means get the stone. Otherwise, you are just throwing your money away into an aspect that your eyes cannot appreciate.

Brett-

September 13, 2017 at 2:18 pm

Hello Paul, I’m currently looking to buy a emerald cut diamond. If it wasn’t emerald cut I wouldn’t be as concerned with the clarity and color. Currently I am looking at VVS1 or higher, G or higher. Am I wasting money when I could go lower because all I’m concerned about is how it looks through the naked eye.

Paul Gian-

September 13, 2017 at 4:26 pm

Depends on what carat size you are looking to buy. I would say that VS1s would be more than enough to ensure eyecleanliness.

Keith-

November 27, 2017 at 1:19 pm

Hi Paul, I was thinking of buying a Cartier 1895 paved round dimond ring platinum, carat . 4ct Colour h, vs1 .. Price 4350 uk pounds do you consider that as best value for that type of ring?

Paul Gian-

November 28, 2017 at 2:21 am

Putting value with branded goods is kind of an oxymoron. For such a small sized diamond ring and priced excessively at 4350 pounds, you can get a better cut diamond and setting at a quarter of those prices.

I would really like your advice, I am purchasing an eternity band. I am not sure if I should go with .40 f sl1 or go with .45 diamonds sl1. which one would have more spark.. Any advise is welcome ty Lynn

Paul Gian-

January 5, 2018 at 3:13 am

Size is not the determining factor of whether a diamond will sparkle or not. Cut quality is. If you are looking for the best sparkle in an eternity ring, go to Brian Gavin or White Flash. They use super ideal cut diamonds for their melee stones.

Jenan-

February 10, 2018 at 1:47 am

Hi there!

We’re looking at one diamond that is VS2, round brilliant, 1.36 I and VS2 round brilliant, 1.46 J. These are comparably priced, and although I like the 1.46 size, the J color turns me off since I’m color sensitive (even though the cut is gorgeous).

The alternative is VS2 round brilliant 1.54 G for around $2000 more. Is this good value? Or do you think there isn’t a big difference between 1.36 and 1.46 size if I’m satisfied with an I color?

Paul Gian-

February 10, 2018 at 4:35 am

The ct weight differences will not be obvious ASSUMING these diamonds have identical cut quality (which I doubt so).

Kelly McCormack-

March 21, 2018 at 4:48 pm

Hello Paul,
First off I’ve read nearly every page and everything you’ve wrote, so please don’t judge me – I already took your advice and own a “real” diamond!
I’m thinking of taking a leap and buying this on line from an established estate seller. (I know I know) However if I don’t like it I can return it, no questions asked and for the full amount – so it’s like ordering clothes on line – try on, if it doesn’t work, return it….
It’s a .91CT Old Miner cut center diamond VS2 clarity/I color. It’s set in platinum with 2, .02 side diamonds of the same quality.
So, a couple of questions:
1. What is an old miner cut? I’ve read a few things about it, but the cut alone sounds like the guy who dug the diamond out of the earth, sat there in the mine and hand cut it!
2. Are you a fan of the old cut diamonds? I understand they were hand cut (and no two alike) vs machine cut, but they hold a type of romance for me.
3. Then there’s the Old European Cut. What’s the difference?
4. I also understand the rules about cut being the most important, but that’s all the info I have.
5. It’s $850 USD, which would be my birthday gift, but should I? Or get something else for the money? I love unique things.
Thanks for listening to all my rambling!
I look forward to your reply.
Kelly

Paul Gian-

March 21, 2018 at 5:49 pm

Let me provide some honest feedback and tips on things to look out for. First of all, who graded the diamond? GIA or some other unreliable lab?

5) It’s really up to you to spend your money but I can tell you that for this amount of budget, the 0.91ct diamond is definitely misrepresented. It’s not going to be an I/VS2 for sure. So, you are going to get ripped off in this purchase. And I already have an answer to the question I posed. GIA definitely didn’t grade this diamond. If the stone’s qualities are accurately represented, there’s no way it is priced like this.

The 1.2ct is priced $950 higher. Those specs above i would have thought the smaller ct would be more. Both options ive found online. Is the difference just bc the ct weight is higher? If so, are either of those spec differences visible to the naked eye?
Thanks!

I am trying to tell the differences between a .8 carat vs 1 carat cushion diamond. How do you account for girdle thickness variations if one is cut with an extremely thick girdle while the other is cut with a thin girdle?

Paul Gian-

June 4, 2018 at 7:12 am

I don’t account for girdle variations since every single fancy shape stone can be polished in a unique manner. Let me ask you: can you tell the difference between .9 carat and 1 carat? If you can, you can definitely see the differences between a 0.80 carat vs 1 carat cushion.

Here’s something else you can do as well. Refer to the grading reports for the corresponding dimensions of the 2 stones. Take a blank piece of paper and sketch the outline in a similar way that I did the tests above.